The wooden panel door derives its name from the fact that it is constructed of separate panels held between vertical stiles and horizontal rails. The stiles and rails are generally milled separately and assembled about the panels to produce a sturdy but elegant door amenable to a variety of finishes including those in which the natural wood is exposed. The use of wood provides good thermal insulation and the broad areas of the stiles allow flexible placement of the lock set and hinges at the construction site with standard wood-working tools.
Nevertheless, the panel door is not well adapted to applications where security is important. Even with a reasonable thickness of lumber and despite the availability of numerous lumber types, a panel door is still readily breached by strong impact which may break the lock set from the lock stile and/or the strike plate from its opposing jamb. Although this may be remedied somewhat by the use of large protective escutcheons, these are not always effective and, by requiring insertion of additional mounting screws into the door stile, escutcheons may in fact further weaken the stile itself. Escutcheons invariably make the door less attractive.
Accordingly, for security sensitive applications, it is typical to use steel doors. Although these doors may have an embossed surface reminiscent of a panel door, they are generally less attractive and more expensive alternatives to a wooden panel door.